NORTH AMERICAN COLEOPTERA. 
165 
The males are narrower, have the tooth of posterior femora larger 
and more acute, and the pygidinm truncate or barely arcuately 
emarginate T\\q females are broader, the femoral tooth is feeble or 
reduced to an almost imperceptible lump, and the pygidinm is 
rounded, not at all emarginate. 
The twenty-five specimens before me vary in size ; in color, two 
having the elytra yellow ; in the sharpness of the truncation of the 
elytra, the outer angle being indistinct in some. 
Length 9 — 11 umi.; .36— .44 iuch. Habitat. — Cal., Wash., Can., Lake Superior, 
Hud. Bay Terr., N. Y. 
Food-plaut unknown. 
D. piibicollis Suffrian. Crotch’s description. 
“ Narrow, elongate seneous ; legs pale red, under surface silvery ; head, thorax 
and scutellum cinereous, pubescent; eyes prominent; thorax longer than broad, 
callus not well marked, surface punetulate ; elytra closely striate puuctate, apex 
rounded, interstices rugulose ; tibiae carinate externally, apex not produced. 
L. .42. Illinois. Very distinct by the rounded elytra, simple femora, and pu- 
hesceut thorax.” 
Mesosternum narrower than the coxa ; first ventral segment longer than the me- 
tasternum ; third joint of antennas much longer than the second. The form is 
convex above and but little flattened beneath. 
The sexes do not tlifter. 
About twenty specimens in different collections present no varia- 
tions. 
Length 10 — 11mm.; .40— .44 inch. Habitat. — Illinois. 
Food-plant, Nymphcea. This species seems to be comparatively 
rare, and is curiously local, every specimen being labeled Illinois, 
or N. Illinois. 
D. piibesceiis LeConte. Original description translated. 
“ Elongate, ferruginous, densely clothed above with sericeous golden hair ; 
thorax quadrate, slightly constricted on each side at middle, broadly channeled 
above, vaguely Impressed before and behind, tubercles broad, hut little promi- 
nent; elytra with the disc depressed, the sides suddenly declivous, towards the 
suture tri-impressed, apex subtruncate, striae strongly punctate, interstices almost 
flat; posterior femora edentate. Length 9 mm.” 
Aleso.stermim narrower than the coxa ; first ventral segment longer than the 
metasternum; third joint of antennae longer than second. 
The males are narrower than the females, anti have the jtygidium 
short and broadly rounded, nearly truncate; the female pygidimn is 
elongate, rounded at tip. 
Three specimens only, present no variations. 
Length 7—9 mm.; .28— .36 iuch. Habitat. — Can., 111., Mich. 
